This invention relates to a magnetron, and more particularly to an internal permanent magnet type magnetron which can be firmly fitted to a microwave-receiving member such as a waveguide or microwave oven (hereinafter referred to as "a waveguide").
Recently developed is a magnetron, in the evacuated envelope of which there are received permanent magnets for creating a microwave-generating electric field, together with, for example, an anode, cathode and filament. Said recently developed internal permanent magnet type magnetron whose evacuated envelope made of magnetic metal is used by itself as the return path of a magnetic circuit, offers the advantages that it is unnecessary to provide a magnetic yoke made of magnetic material in addition to copper evacuated envelope as is the case with the prior art magnetron having permanent magnets disposed outside of the evacuated envelope; the magnetron has a simplified construction; the permanent magnets can be located near an optimum region for creation of microwaves; and the permanent magnets and in consequence the associated magnetic circuit can be made compact. However, the above-mentioned recently developed magnetron lacks proper means for fitting said magnetron to, for example, a waveguide. Therefore, it has been demanded to invent means for reliably fitting said magnetron to, for example, a waveguide. Particularly in recent years when a magnetron is used with a microwave oven widely in the general household, a strong demand has been directed to the development of means for securely mounting the magnetron on the microwave oven, to which the microwave oven may probably be subject during transportation or handling.